Great graphics, great atmosphere, great voice acting, and exhilarating combat are what this game is all about...
Starting with regard to the combat, it is definitely the most unique and smooth combat system in any game that I can recall. It earns its "Freeflow" moniker well: while there only a few moves in the game, nine or ten, I believe, (including the gadgets) it is the way they can be smoothly stringed together in any number of ways that makes the combat enjoyable and intense for hours and hours, with moves such as a batclaw pull and takedowns which instantly knock out enemies. With this uniqueness comes an inevitable learning curve, at least it did for me. In fact throughout almost my first playthrough of the game, I had a bit of trouble towards the end of the game, and it wasn't until I watched a video of combat online that I realized I wasn't even close to utilizing all the moves at my disposal. In an experience that I don't think has ever happened to me before, I actually became quite addicted to the combat only really on my second playthrough, as I had gradually mastered all the moves in Batman's repertoire.
Now on to the environments. As the game takes place on Arkham Island, much of the environments inevitably involve prison cells and the like. Everything from the dimly lit prison cells to the dingy old floors has the effect of making the whole scene unsettling and as if insanity is lurking just around the corner. (Which it usually is- there are guys that jump on top of you and attack Zelda zombie style!) Not since Bioshock have I felt such great atmosphere from the environment.
The music is also done quite well. To my knowledge, the music is all new, composed specifically for the game. It does what music should do: contribute to the emotions you are supposed to feel at a given point in the game. There are clear similarities to previous batman films in terms of the music style, which is nice; for people like me who grew up watching all the batman films, certain musical motifs simply are what batman music sounds like, and the fact that game doesn't try to veer off into a greatly different style is appreciated.
Finally, the voice acting in the game is, as mentioned, superb. In a great move that in fact was what first gave me hopes that this game would be good, three of the voice actors from the excellent Batman animated series of the 1990s reprise their roles. Kevin Conroy is great as Batman, and Mark Hamill shows once more that he is the definite voice of the Joker. The original voice of Harley Quinn also returns to her role.
This is a game that I can honestly say is worth buying. People who have knowledge of the Batman universe will especially appreciate the care taken to the history of the property, but it is ultimately an engaging tale that can be enjoyed even without a prior love for the troubled man in the rubber suit.